22 May
2016
22 May
'16
9:02 a.m.
Background - I have a PDP 11/40 that came to me with a CPU backplane and a
general purpose 4 slot peripheral backplane. The CPU backplane came to me
connected to the 4 slot via a std 11/40 M981. In the 4-slot I have I have
a working 64K solid-state RAM card, M7856 serial card, M9312
bootstrap/console card, and an RL02 drive controller. I can access RAM
from the console, run the console program (monitor
program) off the M9312
through the serial card. I can't boot yet off the RL02
and I am thinking
this is due to a termination issue, not sure yet. I decided I need more
backplane to go any farther.
So I decided to insert two 32K core memory backplanes in between the
original two backplanes that came with the system. My plan is to replace
the solid-state RAM card with core, and this will free up a slot on the
4-slot backplane for a terminator. Am I correct in my logic?
I have connected the "new" backplanes using M920's. Imagine the original
system with a core backplane wedged in the middle. Power seems fine, DC LO
AC LO fine.
Right now there is nothing in the core backplanes, First I want to verify
that I have them arrayed correctly and that I can still communicate with
the (now) 4th backplane in the back. I can run "chase the lights" from the
console but the serial card seems to have stopped working. It appears that
the console program is being loaded and runs from the M9312 but nothing is
appearing on the terminal. I cannot send an "A" to the terminal, the most
basic test I can think of.
Could be the the M7856 card decided to die on me just now, or something
else is wrong. Does anyone have a PDP 11 /05/10/35/40 and have
experimented about what you can and can't do with backplanes?
I know that there are a lot of variables here, so I'd like to start with
the basics
Basic Question #1
Do I need grant cards in *every* empty slot of the core backplane,
including the end slots with the M920's?
Basic Question #2
Can you only use the core backplanes for core memory (assume yes), or are
they capable of holding other types of cards temporarily? (yes/no/maybe)
I am researching the system config on my own, but I thought if anyone had
any advice I'd love to hear it, make troubleshooting a little easier.
I have read up on the subject:
http://retrocmp.com/how-tos/setup-a-pdp-11-unibus-backplane
https://trmm.net/PDP-11
I see this is not a simple little thing. Working to find more GC cards now.
Thanks
b
--
@ BillDeg:
Web: vintagecomputer.net
Twitter: @billdeg <https://twitter.com/billdeg>
Youtube: @billdeg <https://www.youtube.com/user/billdeg>
Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>
22 May
22 May
9:33 a.m.
Strictly the core backplanes are not Unibus backplanes. They have Unibus In
and Out connectors, but the slots are wired for the core memory board,
not Unibus boards (like SPCs -- Small Peripheral Controllers -- which is what
you serial port is).
Basic Question #1
Do I need grant cards in *every* empty slot of the core backplane,
including the end slots with the M920's?
No. In fact in most cases it is wrong to put grant continuity cards in there.
However in a lot of cases a special backplane (like your core memory
one) will have some spare slots (perhaps the core memory doesn't take
up all 9 slots). And DEC often (but not always) wired those so you could
put SPCs in there. In which case you will need grant continuity cards in those
slots if you have nothing else in them.
Basic Question #2
Can you only use the core backplanes for core memory (assume yes), or are
they capable of holding other types of cards temporarily? (yes/no/maybe)
See above. The slots for the core memory and controller cards are special and
can only take those cards. But you might have normal SPC slots on the same
backplane.
You need to find the 'module utilisation chart' for that core memory backplane.
Be warned that DEC normally drew these looking at the _wire side_ of the
backplane, not the side where the PCBs go!
-tony
10:09 a.m.
On Sun, May 22, 2016 at 12:33 PM, tony duell <ard at p850ug1.demon.co.uk>
wrote:
Strictly the core backplanes are not Unibus
backplanes. They have Unibus In
and Out connectors, but the slots are wired for the core memory board,
not Unibus boards (like SPCs -- Small Peripheral Controllers -- which is
what
you serial port is).
Tony,
Are you saying remove all of the GC cards, just leave the slots blank?
Here is a photo of what I have now:
http://vintagecomputer.net/digital/pdp11-40/coreplanes_installed.jpg
remove the gc cards from the core planes? I will read up on this more,
just getting started.
thanks.
Bill
Basic Question #1
Do I need grant cards in *every* empty slot of the core backplane,
including the end slots with the M920's?
No. In fact in most cases it is wrong to put grant continuity cards in
there.
However in a lot of cases a special backplane (like your core memory
one) will have some spare slots (perhaps the core memory doesn't take
up all 9 slots). And DEC often (but not always) wired those so you could
put SPCs in there. In which case you will need grant continuity cards in
those
slots if you have nothing else in them.
10:10 a.m.
Are you saying remove all of the GC cards, just leave
the slots blank?
Yes, from the slots that are designed to take the core memory or its
controllers (I assume, given you have special backplanes, there are
boards with the core planes on, and more boards with the XY drivers
or the sense/inhibit logic on).
Do you have a diagram of where the core boards should go. If so, are
there slots in the backplane left over. What are those 'extra'
slots for?
-tony
10:22 a.m.
The core memory/CPU backplane is a special case and doesn?t need grant cards.
If you have linked up to the expansion Unibus then you need to check you have the NPG
jumper in row C, Pins A1 and B1 in each slot. If these do not have wire wrap then you will
either need to wire wrap them or insert a G727 into the backplane slot. Without these the
units will hang on attempting to use a card that requires DMA access.
Hope this helps.
Mark
On 22 May 2016, at 18:10, tony duell <ard at
p850ug1.demon.co.uk> wrote:
Are you saying remove all of the GC cards, just
leave the slots blank?
Yes, from the slots that are designed to take the core memory or its
controllers (I assume, given you have special backplanes, there are
boards with the core planes on, and more boards with the XY drivers
or the sense/inhibit logic on).
Do you have a diagram of where the core boards should go. If so, are
there slots in the backplane left over. What are those 'extra'
slots for?
-tony
10:23 a.m.
On Sun, May 22, 2016 at 1:10 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
I have core memory cards that fill these backplanes from another system. I
removed the cards, kept them sorted for re-insertion after I get the
backplanes communicating properly. So, this is just a temporary set up.
I wanted to migrate the core to a different 11/40 because I have the CPU
and power supply tested and working. By eliminating power and CPU
variables I can troubleshoot just the core cards one at a time. I have a
few core cards that work so I will be able to work through the unknowns in
this system. The system they came from needs power supply work, etc.
Too many things to try to fix all at once.
Thanks for the help.
--
@ BillDeg:
Web: vintagecomputer.net
Twitter: @billdeg <https://twitter.com/billdeg>
Youtube: @billdeg <https://www.youtube.com/user/billdeg>
Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>
Are you saying remove all of the GC cards, just
leave the slots blank?
Yes, from the slots that are designed to take the core memory or its
controllers (I assume, given you have special backplanes, there are
boards with the core planes on, and more boards with the XY drivers
or the sense/inhibit logic on).
Do you have a diagram of where the core boards should go. If so, are
there slots in the backplane left over. What are those 'extra'
slots for?
-tony
3136
days inactive
3136
days old
5 comments
3 participants
participants (3)
-
ard＠p850ug1.demon.co.uk -
billdegnan＠gmail.com -
mark.darvill＠mac.com